1. Technical Field
The present invention relates to an image forming apparatus, and an image forming method.
2. Related Art
As an image forming apparatus which ejects a liquid to form an image on a printing material, for example, an ink jet printer is known. In such a printer, a nozzle row formed by arranging a plurality of nozzles for ejecting a liquid is provided for each color of liquid. It is known that images are formed to overlap by partially using each nozzle row. For example, in WO2005/105452, a subsidiary image (for example, a background image) and a main image are formed to overlap on a printing material by using a nozzle row divided in half.
As described above, when viewing the image in which the main image and the subsidiary image are formed to overlap, the coloring property may be damaged according to a light state corresponding to a printed object. For example, when the front face (for example, a printing face) of the printing material is irradiated with light, as the subsidiary image (the background image) gets thicker, the coloring property of the main image printed thereon gets more satisfactory. However, when the back face (for example, the face opposite the printing face) of a printing material such as a printed object for illuminated advertising is irradiated with light and an image is viewed from the front side, the light is further blocked as a subsidiary image gets thicker, and thus the coloring property of the main image deteriorates.